I've not voted but I'm thinking of doing so: Is MDPI a reputable Academic Publisher?
Reason is that MDPI has grown really big. It's roughly the fifth biggest publisher overall now, which is incredible considering that it was much smaller (~17th in 2015). It's arguable that How to identify predatory publishers/journals (the "duplicate" question) works as an answer for small publishers, since there are so many of them and they are often very similar to each other. However, there aren't many publishers of MDPI's size. They attract attention from other publishers (example), and there are more facts about them available (e.g. their annual report).
The question also has close to 100k views as of time of writing in spite of being closed.
I wonder what others think about this.